1. Field of the Invention
The present invention relates to an image forming apparatus that has a normal mode in which power is supplied to every component in the image forming apparatus and a power-saving mode in which power is supplied to only some of the components in the image forming apparatus.
2. Description of the Related Art
Devices with low-power consumption are in demand; therefore, research has been conducted in the field of image forming apparatuses, such as facsimile machines, printers, and copiers, into saving power when the apparatuses are on standby, for example, standby for receiving, standby for copying, and standby for printing.
Various solutions offering power savings are widely used in image forming apparatuses. These solutions include, from the mechanical viewpoint, stopping mechanical processes completely during standby situations and, from the electrical viewpoint, shifting from normal mode to power-saving mode, in which power is supplied only to essential logic circuits.
In addition to power saving, there has also been a demand to decrease a reset time of image forming apparatuses. The reset time is a time that an image forming apparatus takes to shift from power-saving mode to normal mode. Japanese Patent Application Laid-open No. 2006-38916 discloses a technology that forms an image on a recording sheet in such a manner that the maximum amount of toner forming the image is set smaller than usual. Using this technology makes it possible to prevent fixing failures and decrease the reset time, which leads to both power saving and improved productivity.
In the image forming apparatus disclosed in Japanese Patent Application Laid-open No. 2006-38916, a controller and an engine are connected to each other via a universal bus that establishes communication between the controller and the engine. In this configuration, when the image forming apparatus is powered, it is necessary to first establish communication between the controller and the engine via the universal bus and then send a mode-shift command from the controller to the engine before the engine shifts the power mode from power-saving mode to normal mode. However, this process lengthens the reset time. There is a need to shorten the reset time.